Objective To investigate the effects of N-acetylserotonin (N-AS) on the expression of active caspase-3,Bcl-2 and Bax in rat retinas induced by retinal ischemia-reperfusion injury (RIRI).Methods Adult male Sprague-Dawley rats were randomly divided into the normal control group (6 cases),RIRI group (30 cases) and NAS group (30 cases),RIRI models in NAS group were established after giving NAS,the groups were sub-divided into 6 hours,12 hours,24 hours,48 hours and 72 hours group based on the time of RIRI.Morphologic changes were evaluated by HE staining.The expression of active caspase-3,Bcl-2 and Bax protein in the retina of rats was detected by immunohistochemistry.Results HE staining showed that the retinal structure in the normal control group was clear,and the cells in each layer were tightly packed;Each layer of retina was edema in the RIRI group after 6 hours and 12 hours,the edema gradually alleviated after 24 hours,the ganglion cells decreased gradually,the distribution was in disorder,with the prolongation of time,the retinal ganglion cells were defected;drug group of as Compared with RIRI group,the cell edema in the NAS group at 6 hours and 12 hours were obvious reduced,the cells in 24 hours,48 hours,72 hours group arranged regularly,the loss number of ganglion cells were reduced.The number of active caspase-3 positive cells in RIRI group increased at 6 hours after peffusion,the number was (561.15 ±37.19) cell ·mm-2,and reached the high level at 24 hours,the number was (1522.61 ±84.36) cell · mm-2,and then decreased gradually.The number of active caspase-3 positive cells in NAS group was significantly lower than that in RIRI group,the difference was statistically significant (all P ＜ 0.05).The expression of Bcl-2 positive cells in RIRI group began to decrease after 6 hours,and decreased to a low level at 24 hours,and the number of Bcl-2 positive cells in NAS group was significantly higher than that in RIRI group at each time point,the differences were statistically significant (all P ＜ 0.05).There were almost no Bax positive cells in the retina of the control normal group,and the Bax positive cells were found to be higher of the RIRI group at the 6 hours after RIRI,and reached the higher level at 24 hours,and decreased at 48 hours.The Bax positive cells of NAS group were significantly less than those in the RIRI group at different time points,and the differences were statistically significant (all P ＜0.05).Conclusion NAS can promote the expression of Bcl-2 protein in rat retina after RIRI,inhibit the expression of Bax protein,decrease the expression of active caspase-3 protein,alleviate cell apoptosis,and have neuroprotective effects.%目的 探讨N-乙酰-5-羟色胺(N-acetylserotonin,NAS)对视网膜缺血再灌注损伤(retinal ischemia-reperfusion injury,RIRI)大鼠视网膜活性Caspase-3、Bcl-2、Bax表达的影响.方法 取健康成年Sprague-Dawley大鼠66只,采用随机数字表法随机分为正常对照组(6只)、缺血再灌注组(30只)与药物组(30只),药物组于造模前30 min腹腔注射5 mg·kg-1NAS,缺血再灌注组腹腔注射同等剂量的生理盐水,缺血再灌注组与药物组按RIRI后时间,分为6h、12 h、24 h、48 h、72 h五个亚组.采用HE染色法观察各组视网膜形态学变化,免疫组织化学染色检测各组大鼠视网膜活性Caspase-3、Bcl-2及Bax蛋白表达.结果 HE染色显示正常对照组大鼠视网膜结构清晰,各层细胞排列紧密;缺血再灌注组大鼠RIRI后6h、12 h视网膜各层高度水肿,24h后水肿逐渐减轻,神经节细胞逐渐减少,分布较紊乱,随着时间延长,视网膜神经节细胞大片缺失;药物组6h、12h较缺血再灌注组细胞水肿明显减轻,24h、48 h、72h组较缺血再灌注组细胞排列规整,神经节细胞数量减少减轻.缺血再灌注组视网膜活性Caspase-3阳性细胞数在灌注后6h开始表达增加,阳性细胞数为(561.15±37.19)个·mm-2,24 h达到较高水平,阳性细胞数为(1522.61±84.36)个·mm-2,随后逐渐下降,药物组视网膜各时间点活性Caspase-3阳性细胞数均显著少于缺血再灌注组,差异均有统计学意义(均为P＜0.05).正常对照组视网膜可见大量Bcl-2阳性细胞;缺血再灌注组RIRI后6 h Bcl-2阳性细胞开始下降,12h后继续减少,24h降至较低水平;药物组各时间点Bcl-2阳性细胞数均显著多于缺血再灌注组,差异均有统计学意义(均为P＜0.05).正常对照组大鼠视网膜几乎未见Bax阳性细胞;缺血再灌注组RIRI后6h神经节细胞层及内核层可见Bax阳性细胞,24h达到较高水平,48 h开始下降;药物组各时间点Bax阳性细胞均显著少于缺血再灌注组,差异均有统计学意义(均为P＜0.05).结论 NAS可促进RIRI大鼠视网膜Bcl-2蛋白的表达,抑制Bax蛋白的表达,降低活性Caspase-3蛋白表达,减轻细胞凋亡,具有神经保护作用.
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